Cement-based materials (CBMs) such as mortar and concrete are the materials most frequently used by the building industry. Per year an amount of 10 billion tons of concrete is produced, highlighting the economic relevance of CBMs. In Germany up to 28 billion Euros are going to be spent in repair and maintenance works on railway bridges, mostly by replacing corroded or damaged concrete structures. A main cause of CBM damage is water penetration which is considered as perpetual problem in civil engineering. CBMs typically suffer from invading water which corrodes load-bearing elements that are integrated into the volume of the material. Micro cracks, e.g. due to freeze-thaw-cycles, and the porous material property render the cementitious material further vulnerable towards water ingress and expose building structures to large quantities of water intake over time. Absorbed water further promotes corrosion on
the embedded steel structures (Bentur et al., Steel Corrosion in Concrete: Fundamentals and civil engineering practice. Spon, 1997).
Existing strategies to render cement-based materials more water-resistant often require a surface treatment of the material after the casting process and the use of organic solvents to achieve a bulk modification of the CBMs with hydrophobic agents. In particular, silane-based additives such as alkoxysilane, alkoxysiloxane, alkali siloconate or silicone resins are used for subsequently hydrophobizing CBMs, as disclosed, for example, in WO 2007/051833 or EP 0177824. Such a modification after the casting process is supposed to reduce the water ingress. However, in order to be efficient, the modification of the material surface has to be complete and without any gaps. It is hence costly and time consuming. Moreover, silane-based hydrophobic agents often require the use of organic solvents which may evaporate from the materials over a prolonged period of time and may thus constitute a potential health hazard.
There is thus a need for an alternative approach to provide cement-based materials with increased wetting resistance which does not require a laborious post-processing or may lead to health or environmental problems over a long period of time. The process to provide said cement-based material should be economical, safe and suitable to prepare large batches of material suitable for a variety of applications.